Yeah, this is actually quite fun for me too.
Hmmmm... Ya know, I take back what I said about what might be behind the engine room grill. After watching a number of first season episodes last night I get the distinct impression that this was the intended size the viewer was supposed to assume. Engineering was mainly designed to help sell the overall size of the ship.
Further, when I drop in some of my estimates of where hull pressure compartments would be on the secondary hull, it turns out that there is a nice space for the large engine equipment to fit in on that deck. Could be coincidence, but it does work out nicely.
On the subject of TAS elements... most likely no. But then again, I'm not going to fill in every space on the ship. So anyone wanting to attempt to apply TAS elements to open areas not occupied by live actions sets should feel free.
had two engine rooms in his plans, and I don't see any good reason to think that this couldn't be the case... there does seem to be room.
One of the factors that led me to putting the main engine room where I put it was the placement of the dilithium crystal articulation matrix chamber (that big doohickey in the middle of the room that showed up in the second season). That hummer in the middle of the room indicates to me that it's somewhere in between the warp core and the nacelles (the dueling references of whether or not the engine room was near the warp drive or the impulse engines further led me to decide that the big tube assembly wasn't a part of either
system; rather, it's a power distribution system that sends energy to both systems, thus covering the apparent contradiction in references) and therefore, the big glowy tube thingy is forward, and the door is aft.
Putting the first season engine room forward was a) a way of dealing with the major differences in the contours of the room between the first and second seasons, and b) a joke that actually made a lot of sense the more I thought about it.